As responding to various environmental regulations emerged as a major issue in the global IT market, various attempts such as consolidation, virtualization, optimization, and leverage etc. are being made to increase the efficiency in managing the vast amount of energy consumed to maintain data centers and storage devices.
NomadFS is an embodiment of PDC, which manages access frequencies of files using multi cues. Herein, each cue is mapped with a disk and moves the files in each cue to the corresponding disk. The most upper cue contains files with the highest frequencies and may continue using the mapped disk, while the use frequency of the disk mapped with the lowest cue is reduced and spinned-down.
This method reduces the power consumption of the disks having files with low access frequencies, but may overload some of the other disks, thereby decreasing the overall performance.
PARAID and Energy-Efficient Framework also have problems since they do not take into consideration the characteristics of data such as access frequencies. On the other hand, MAID is a method which stratifies storage devices into layers to differentiate power consumption and selects the data to be located in each storage device. PDC uses a method of stratifying power consumption of storage devices based on their data access frequencies.
However, it is necessary to seek a way to provide a RAID method having an even lower power consumption rate, besides the above methods.